Decorative finish

ABSTRACT

A decorative finish is applied to substrate material such as leather by a process which comprises forming on the substrate, a coating comprising an aqueous resin/pigment dispersion (a) and a liquid (b) which is substantially immiscible with dispersion (a) under the conditions of the forming and which is not an aqueous component. Preferred resin materials are the polymers and copolymers of acrylic acid, methacrylic acid, and itaconic acids and polymers and copolymers of esters and amides of the same acids.

Unlted States Patent 1 1 1 3,719,517

Gladstone et a1. 1 1 March 6, 1973 DECORATIVE FINISH [56] References Cited [76] Inventors: James E. Gladstone, 37 Western UNITED STATES PATENTS Way, Whitley Bay, Northumberland; James E. Wilcox, 3 woodbum 3,382,089 5/1968 Klein et al. ..117/45 x Close, winlawn Co Durham; John 3,553,008 1/1971 Reischl et a1. 17/142 x Hawthorn, Dunnegan amide BM 3,388,087 6/1968 Dieterich et a1 ..117/142 x 2,868,741 1/1959 Chambers et al.... .....260/29.4 ux

Icy Durham an England 2,865,878 12/1958 Toothill et a1 ..260/29.6 E

Filed: July 22, 1970 Appl. No.: 57,368

Foreign Application Priority Data Sept. 17, 1969 Great Britain ..45,937/69 US. Cl. ..l17/37 R, 117/45, 117/76 R, 117/120, 117/142, 117/161 P, 117/161 UC, 161/226, 161/247, 260/296 R Int. Cl., ..B44d 5/06 Field 01 Search ..260l29.6 R; 117/37 R, 120, 117/142, 76 R, 76 P, 161 P,161UC,161 UE, 45; 161/226, 247

Primary Examiner-Edward G. Whitby An0mey-George Simmons, Carl A. Castellan and Philip D. Freedman [57] ABSTRACT 14 Claims, No Drawings DECORATIVE FINISH The invention relates to a process for providing a decorative finish on a substrate, particularly but not exclusively on a pelt prepared for use, such as leather.

Pelts are conventionally prepared for use by tanning and dressing. Leathers so prepared may then be treated with resins to further modify their physical properties and these resins are often applied in dispersions with pigments. The processes conventionally used for applying liquid resin/pigment dispersions include padding, spray coating and curtain coating. Leathers of the color of the last pigment applied result from such processes. When more than one color is to be applied to the leather to provide a multicolored pattern thereon, the leather is often embossed before the final pigment is applied, and the last application of color is controlled so that the final pigment concentrates either on raised portions or in valleys of the embossed design. The leather is then stretched to bring out the color in the valleys.

The process of the present invention has the advantage that decorative patterns can be applied simply and inexpensively to substrates, particularly to leathers.

According to the invention there is provided a process for providing a decorative finish on a substrate which process comprises forming on the substrate a coating comprising an aqueous resin/pigment dispersion (a) and a liquid (b) which, under the conditions of application of dispersion (a) and liquid (b), is substantially immiscible with dispersion (a). The liquid (b) may or may not contain a pigment. The coating is subsequently dried to produce an unusual and pleasing color design.

The substrate material suitable in the present invention is any material which is of a nature, or has been treated to be of such a nature, as to prevent or restrict penetration of liquid (b). Suitable substrate materials include treated paper; pelts prepared for use, such as parchment and leather; synthetic materials used as leather substitutes, such as poromeric materials; and

other plastics materials. The particularly preferred substrate is leather.

Applying a decorative finish to leather presentssome difficulties not encountered in the coloring of textiles. Unlike many textiles, leather is not a homogeneous product of definite composition whose chemical properties may be closely and accurately defined, but is rather a product derived from protein collagen treated with tanning agents. Although the chemical characteristics and properties of collagen have been determined, the variety of materials that will convert it into leather leave the final composition of the leather indefinite. Furthermore, not only are the materials used to convert hide to leather of a wide variety, but also the quantities used, the method of application and the physical condition of the hide prior to tanning or coloring are of a great'variety, each factor affecting the coloring properties of the resulting leather. The present invention provides a procedure for coloring leathers with unusual patterns of vividly colored coatings of ex cellent adhesion and wet-rub resistance.

Hatton et al., U.S. Pat. No. 2,865,877, issued Dec. 23, 1958, discloses coating compositions adapted to be applied to a variety of porous substrates such as leather. In accordance with the invention of Hatton et al., an ammonium or volatile amine salt of a linear copolymer of an ester of acrylic, methacrylic or itaconic acids is mixed with a linear copolymer of maleic anhydride and a branched chain unsaturated hydrocarbon, and is further mixed with a water-insoluble ethylene oxide condensate, or methyl or ethyl ethers thereof. The resulting composition is applied to substrates as a coating. The compositions may be modified by the incorporation of pigments, dyestuffs, or the like. Application, of a liquid which is substantially immiscible under the conditions of application;

with the resin and pigment dispersion, to produce color designs is not disclosed in the patent.

Toothill, Jr. et al. U.S. Pat. No. 2,865,878, issued Dec. 23, 1958, discloses coating compositions for forming pigmented films on substrates, such as leather. These compositions comprise a salt of a linear copolymer from maleic anhydride and a branchedchain unsaturated hydrocarbon or terpene; and, in addition to this salt, a water-insoluble ethylene oxide condensate or ether thereof. The compositions may contain pigments. Again application of a liquid which is immiscible under the conditions of application with the resin and pigment dispersion to produce the unique color designs is not disclosed.

Neither the l-latton et al. nor the Toothill, Jr., et al. patent discloses the formation of the particular coating of aqueous resin/pigment dispersion and substantially immiscible (under the conditions of application) liquid (b). However, compositions and proportions of components disclosed by these patents may be used and, in fact, are preferred as suitable aqueous resin/pigment dispersions in the present invention. Generally, the choice of resin is not critical and any of the resin/pigment materials conventionally used for coloring substrates are suitable. The resin may be a single resin or a mixture of resins and may be any resin which is filmforming under the conditions the substrate can withstand. For example, in the case of leather up to C., e.g., at room temperature, for up to 5 minutes with the application of plating at pressures of up to 30,000 lb/in', can be used as suitable coating conditions.

Suitable resins include, but are not limited to, polymers, including copolymers, of acrylic acids, methacrylic acids, and itaconic acids, and polymers and copolymers of esters and amides of the same acids. Thus suitable resins include polymers and copolymers of normal and branched-chain alkyl esters, such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, hexyl methacrylate, stearyl methacrylate, etc.; esters of olefinic alcohols, e.g., allyl acrylate, 2-methylallyl acrylate, 2-butenyl acrylate, methylallyl acrylate, 2-chloroallyl acrylate, etc.; amino esters such as 2-(dimethylamino)ethyl acrylate, 2- (diethylamino)ethyl acrylate, 3-(diethylamino)propyl methacrylate, etc.; esters of ether alcohols such as 2- methoxyethyl acrylate, 2-ethoxyethyl methacrylate, 2- isopropoxyethyl acrylate, etc.; cycloalkyl esters such as cyclohexyl acrylate, 3-methylcyclohexyl methacrylate, etc.; esters of halogenated alcohols such as 2- bromoethyl acrylate, 3-chloropropyl acrylate, etc.; nitroalkyl esters, such as 2-nitroethyl acrylate, 2- nitropropylacrylate, etc.; and glycol acrylates such as amides, such as acrylamide and methacrylamide, etc.

The preferred acrylic resins are the polymers and copolymers of ethyl acrylate, butyl acrylate, methyl methacrylate, methacrylic acid and acrylamide.

The aqueous resin/pigment dispersion (a) may include other additives such as binders, foam control agents, dulling agents, wetting agents, etc., conventionally found in pigment compositions.

The resin/pigment dispersion mixture may be formed by working the components into a suitably dispersed condition by grinding in a mill, such as a pebble mill, colloid mill, a high speed stone mill or a high shear mixer.

. The resin/pigment dispersions may be applied to the substrate by any suitable means including dipping, roller coating, application by brushes, padding, spray coating and curtain coating. The liquid (b) may be applied by the same means as the resin/pigment mixture and particularly may be applied by spotting or the like. The dispersion (a) and liquid (b) may be applied in any desired sequence so long as the first applied component has not substantially dried when the second component is applied. Dispersion (a) and liquid (b) may be applied at substantially the same time. Preferably, dispersion (a) is applied as the first component followed by a selective or random application (spotting) of liquid (b) while the first applied dispersion is still wet. Under these conditions of application, the liquid (b) may draw back into areas of concentration either connected or unconnected to each other. Such areas are called retraction spots.

In another application sequence according to the present invention the substrate is first coated with liquid (b). Then, while liquid (b) is still wet, a coating of the aqueous resin/pigment dispersion (a) is applied. Since there will not be uniform mixing of the dispersion (a) and liquid (b the pigment contained in (b) will not be uniformly distributed over the substrate surface, and

indeed should preferably not be present at all on some parts of the surface. In such places the base color of the substrate (which may have been previously pigmented) will show. Such a process may conventionally be carried out'in a double curtain coating process whereby the substrate passes in turn through curtains of liquid (b), then dispersion (a).

If it is desired to introduce a further color into the pattern the process may be repeated. However, the preferred alternative it to use more than one pigment in the dispersion (a), the pigment being chosen to separate and give what is known as flotation effect" which results in areas of color of each individual pigment in addition to areas of color of the mixed pig-' ments.

The suitable proportions of liquid (b) to dispersion In a preferred embodiment of the present invention, liquid (b) is chosen from liquids which are immiscible with aqueous dispersion (a). In a coating process which involves a substantial amount of agitation of the liquids on the substrate such as inpadding, the resin/pigment dispersion and the liquid (b) should be immiscible. On the other hand partial miscibility is allowable when the coating process involves less agitation of the components together on the substrate, as for example in curtain coating.

In this specification the term miscibility shall mean mutual solubility in all proportions. The standards of miscibility and immiscibility shall be those used for determining the classifications found on page C-687 of the Handbook of of Chemistry and Physics, College Edition, 47th Edition, l966l 967. These classifications are made by shaking together 5 ml. of each of two solvents in a test tube for 1 minute, then allowing the mixture to settle. If no interfacial meniscus is observed, the solvent pair is considered miscible. If such a meniscus is present, the solvent pair is regarded as immiscible. As pointed out by the Handbook of Chemistry and Physics, the classification of immiscibility is a qualita tive one since solvent pairs may exhibit some degree of partial miscibility while existing as separate phases. In this specification, miscibility and immiscibility shall means the classifications as determined by the standards of the Handbook of Chemistry and Physics under the conditions of formation on the substrate of the coating of dispersion (a) and liquid (b). Furthermore, in the present specification the term substantially immiscible" shall include pairs of dispersions (a) and liquid (b) that are immiscible and pairs that are partially miscible, while the term immiscible shall include only those pairs that would be classified such by the Handbook of Chemistry and Physics. Also for the purposes of the present invention, the term liquids shall mean those components thatwould be liquid under the conditions of formation of the coating.

Examples of liquid (b) which have been found to be suitable include organic solvents and other organic liquids andwater containing surface active agents. In some coating processes, water has been found to be useful so long as there is little agitation of the resulting two components. It is preferred however that the liquid (b) is not an aqueous component. Suitable liquids thus broadly include water, water containing anionic and/or non-ironic surface active agents, machine oil, solvent naphtha, dipentene, toluene, 2-methoxy ethanol, 2- ethoxy ethanol, 2-butoxy ethanol, methanol, isopropanol, butanol, propylene glycol, hexylene glycol, diacetone alcohol, acetone and other dispersions or solutions of film-forming or non-film-forming components which are immiscible or substantially immiscible with the particular aqueous resin/pigment dispersion (a).

Pigments suitable for use in the process of the invention are those conventionally used, for example disperse and casein band pigments. The term pigment" is here used to cover powder or powdered substances which are mixed with liquids to form paints, enamels and other coating compositions or the like, and which are insoluble in the liquids, and which provide covering, hiding, filling, delustering, dulling and/or coloring action. Since aqueous suspensions or dispersions of pigments are used in the resin/pigment dispere sion (a), it is necessary that such pigments be insoluble in water. If pigments are used in liquid (b), they may or may not be water insoluble. Generally the pigments are in the finely divided forms available in commerce and are frequently ground or precipitated in a form to pass a 325-mesh screen.

Suitable pigments include, but are not limited to, white lead, zinc oxide, titanium pigments, lithopone, other zinc sulfide pigments, barium sulfate, calcium carbonate, silica, talc, mica, and clays, such as china clay. Pigment pastes normally comprise one or more of these or equivalent pigments. There may be added one or more insoluble inorganic or organic colors, such as iron oxide, carbon black, cadmium sulfide, toluidene red, lithol toner, chrome orange, chrome yellow, Hansa yellow, chrome green, phthalocyanine green, phthalocyanine blue, etc.

After application of the final component whether it be dispersion (a) or liquid (b), the coated substrate is dried either in the atmosphere at normal temperatures or preferably at elevated temperatures such as from 60 to 100 C. or higher depending upon the substrate and the time available.

Other coats may be applied to the substrate before or after the process of the present invention. For example in the case of leather one or more further transparent protective coats, such as lacquer coats may be applied if necessary after plating. v

The present invention also includes the coated articles which are the product of the process of applying to a sheet substrate an aqueous resin/pigment dispersion (a) and a liquid (b) which is not a resin/pigment mix-v ture and which is substantially immiscible with the resin/pigment dispersion (a) under the conditions of the application. The coated articles of the present invention cannot be described by reference to their components because of the difficulty of defining a coating film of irregular character (obtained by the present invention) in terms of its elements. For this reason the articles of the present invention are described as products of the defined process.

The invention will be particularly described in and by the following examples which are given for the purpose of illustration, the parts and percentages being by weight unless otherwise stated.

EXAMPLE 1 A side leather sample was finished with a mix of (i) 250 parts of a 35% solids aqueous dispersion of an emulsion copolymer of 60:33:7, ethyl acrylatezbutyl acrylatezacrylamide, (ii) 250 parts of an aqueous dispersion (41 percent solids) of a blue pigment produced by adding an ultramarine blue pigment to an aqueous mixture of sulfonated tallow, hexylene glycol, ammonia and a styrene/maleic anhydride copolymer, and (iii) 500 parts of water. During the finishing step the leather sample was padded with the solution, dried, padded again, dried and plated at 80 C. under heavy pressure.

The sample was then padded with a 1:1 2-butoxyethanolzwater mix and, while still wet was passed through a curtain coater depositing 8 gms/sq. ft. of a mixture which was (i) 165 parts of a 35 percent solids aqueous dispersion of finely divided 6013327, ethyl acrylatezbutyl acrylate: acrylamide copolymer, (ii) 165 parts of a 46 percent solids aqueous dispersion of an emulsion copolymer of about 67:32:1 ethyl acrylatezmethyl methacrylatezmethacrylic acid, (iii) 330 parts of 36 percent solids aqueous dispersion of a red pigment prepared by adding a medium cadmium red lithopone pigment to an aqueous mixture containing sulfonated tallow, oleic acid, ammonia, a styrene/maleic anhydride copolymer and preservatives, and (iv) 340 parts of water the viscosity of the mixture being increased to 22 sec (No. 4 Ford Cup) with a 20 percent solids solution of an ammonium salt of an ethyl acrylate:methacrylic acid (about 31:69 weight ratio) copolymer.

The resulting colored leather sample was charac terized by a pattern of red retraction spots on a predominantly blue background. The sample was dried and finished by spraying with a coat of (i) parts of a 42 percent solids aqueous dispersion of an emulsion copolymer of ethyl acrylate and vinylidene chloride (35.5:64.5 (ii) 75 parts of a 35 percent solids aqueous dispersion of an emulsion copolymer of ethyl acrylatezbutyl acrylatezacrylamide (60:33z7), (iii) 50 parts of an aqueous dispersion containing about 14 percent of a copolymer of ethyl acrylate and methacrylic acid (87:13), about 3 percent of an ammonium salt of a copolymer of diisobutylene with maleic anhydride (1 :1 mol ratio) and 3 percent of octylphenoxyethanol, (iv) 50 parts of a 10 percent casein solution, and (v) 750 parts of water. The sample was plated at 60 C. under heavy pressure and topped with a final cross spray of 500 parts of an aqueous emulsion of a nitrocellulose lacquer and 500 parts of water.

The final sample retained the unusual color pattern described above. The vividly colored coating showed excellent adhesion and wet-rub resistance.

This example illustrates the embodiment of th present invention for providing a decorative finish on leather wherein Z-bqtoxyethanol and water as liquid (b) was first coated onto the substrate sample followed by the addition of a resin/pigment dispersion (a). Inthis case the liquid (b) was partially miscible with the dispersion (a).

EXAMPLE 2 A side leather sample was finished in a manner similar to that of Example 1 with a mix of (i) 250 parts of a 40 percent solids aqueous dispersion of an ethyl acrylate and methyl methacrylate (:15) copolymer, (ii) parts of a 41 percent solids aqueous dispersion of the blue pigment of Example 1, (iii) 125 parts of an ochre yellow pigment dispersion (41 percent solids) prepared by adding a Mopico Premium yellow orange pigment to an aqueous mixture of a surfactant, sulfonated tallow, oleic acid, ammonia, a preservative and a styrene/maleic anhydride copolymer, and (iv) 500 parts of water.

After drying and plating, the sample was padded with Z-butoxyethanol and, while wet, passed through a curtain coater gently depositing 8 gms/sq. ft. of a thickened mix which was (i) parts of a 35 percent solids aqueous dispersion of an ethyl acrylatezbutyl acrylatezacrylamide (6023327) copolymer, (ii) 150 parts of a'46 percent solids aqueous dispersion of an ethyl acrylate/methacrylic acid (about 67:33) emulsion copolymer, (iii) 100 parts of the binder of Example 1,

- described:

EXAMPLES 3 TO 5 In the following examples leather samples were finished by padding with two coats of an aqueous resin/pigment dispersion followed by plating at 80 C. with heavy pressure. A black and white aqueous curtain coating dispersion was prepared and leather samples were processed as follows with the results as The samples were passed through a curtain coater EXAMPLES 6 TO 25 Other pieces of finished leather were initially completely padded over with the various liquids (b) listed in the following table. The pieces were then passed through a curtain mix which was 500 parts of a white pigment emulsion 1000 parts of an aqueous black pigment dispersion and 1000 parts of an aqueous acrylic resin dispersion with the results as follows:

Liquid Description of mm an aromatic solvent prepared varying size of spots with from petroleum some color variation toluene large areas clear of top coat little or no gradation of color 2-methoxyethanol a good number of small areas 5 cleared of top coat areas cleared of top coat, but

remain connected, with rays of top coat material going into cleared areas little complete uncovering of base coat but a considerable gradation in color a pattern of very small cleared areas a complex and largely interconnected pattern of cleared areas bridged at intervals with top coat a similar but less defined pattern than that produced by isopropanol complex pattern with a large number of small areas cleared of the top coat surrounded by an intricate design of top coat a pattern similar to that of ethoxyethanol retraction spots Z-ethoxyethanol Z-butoxyethanol methanol isopropanol butanol hexylene glycol diacetone alcohol The following combinations were used in the preced ing process as liquid (b) with the results as indicated:

Liquid (b) Description of Pattern isopropanol and similar to that of hexylene hexylene glycol glycol isopropanol and propane similar to that of hexylene 1:2 di-ol glycol isopropanol and 2-butoxy few areas cleared to base coat ethanol 5% sodium alkylaryl ether overall pattern of small clear sulfate anionic surfactant areas 10 ditto cleared areas generally somewhat larger than those of 5% mixture 20% ditto finer pattern than 5% mixture l0% anionic surfactant small cleared area over surface,

in oil interspersed with larger clear areas which showed rays of top finish running into center very similar to 10% mixture but large areas were fewer in number and smaller in area massive retraction to give a connected network of top finish showing black flotation. Cleared areas were rayed as described above 20% anionic surfactant soluble oil alkylaryl polyether alcohol nonionic surfactant These examples illustrate the wide variety of components useful as liquid (b) in the present invention.

What is claimed is:

l. A process for providing a decorative finish on a substrate which comprises forming on said substrate a coating'comprising an aqueous resin/pigment dispersion (a) and a liquid (b) which is substantially immiscible with said dispersion under the conditions of forming and which is not an aqueous resin/pigment dispersion; and subsequently drying the coating on the substrate.

2. The process of claim 1 in which said forming comprises first applying to said substrate an aqueous resin/pigment dispersion (a) then, before said resin/pigment has substantially dried, applying a second liquid (b) which is not an aqueous resin/pigment dispersion.

3. The process of claim 1 in which said forming comprises first applying to said substrate said liquid (b) which is not an aqueous resin/pigment dispersion and then, before said liquid has substantially dried, applying said aqueous resin/pigment dispersion (a).

4. The process of claim 1 in which said forming comprises substantially simultaneously applying to said substrate both said resin/pigment dispersion (a), and said liquid (b) which is not aqueous resin/pigment disper- 5. The process of claim 1 in which said substrate comprises leather.

6. The process of claim 1 in which said resin/pigment dispersion (a) is an acrylic resin/pigment mixture.

7. The process of claim 6 in which said acrylic resin is selected from the group consisting of the polymers and copolymers of ethyl acrylate, butyl acrylate, methyl methacrylate, methacrylic acid and acrylamide.

8. The process of claim 1 in which said liquid (b) is applied in a weight proportion to said dispersion (a) of 2:1 to 1:100.

9. The process of claim 1 in which said liquid (b) is applied in a weight proportion to said dispersion (a) of 1:1 to 1:10.

10. The process of claim 1 which additionally comprises drying said formed coating at a temperature from 60 to C.

11. The process of claim 1 in which said liquid (b) additionally contains a pigment.

12. An article of manufacture comprising a coated substrate which is the product of the process of applying to the substrate an aqueous resin/pigment liquid dispersion (a) and a liquid (b) which is immiscible with said resin/pigment dispersion (a) under the condition of said application, and subsequently drying.

13. The article of manufacture of claim 12 in which F It 

1. A process for providing a decorative finish on a substrate which comprises forming on said substrate a coating comprising an aqueous resin/pigment dispersion (a) and a liquid (b) which is substantially immiscible with said dispersion under the conditions of forming and which is not an aqueous resin/pigment dispersion; and subsequently drying the coating on the substrate.
 2. The process of claim 1 in which said forming comprises first applying to said substrate an aqueous resin/pigment dispersion (a) then, before said resin/pigment has substantially dried, applying a second liquid (b) which is not an aqueous resin/pigment dispersion.
 3. The process of claim 1 in which said forming comprises first applying to said substrate said liquid (b) which is not an aqueous resin/pigment dispersion and then, before said liquid has substantially dried, applying said aqueous resin/pigment dispersion (a).
 4. The process of claim 1 in which said forming comprises substantially simultaneously applying to said substrate both said resin/pigment dispersion (a), and said liquid (b) which is not aqueous resin/pigment dispersion.
 5. The process of claim 1 in which said substrate comprises leather.
 6. The process of claim 1 in which said resin/pigment dispersion (a) is an acrylic resin/pigment mixture.
 7. The process of claim 6 in which said acrylic resin is selected from the group consisting of the polymers and copolymers of ethyl acrylate, butyl acrylate, methyl methacrylate, methaCrylic acid and acrylamide.
 8. The process of claim 1 in which said liquid (b) is applied in a weight proportion to said dispersion (a) of 2:1 to 1:100.
 9. The process of claim 1 in which said liquid (b) is applied in a weight proportion to said dispersion (a) of 1:1 to 1:10.
 10. The process of claim 1 which additionally comprises drying said formed coating at a temperature from 60* to 100* C.
 11. The process of claim 1 in which said liquid (b) additionally contains a pigment.
 12. An article of manufacture comprising a coated substrate which is the product of the process of applying to the substrate an aqueous resin/pigment liquid dispersion (a) and a liquid (b) which is immiscible with said resin/pigment dispersion (a) under the condition of said application, and subsequently drying.
 13. The article of manufacture of claim 12 in which said resin/pigment dispersion (a) is an acrylic resin/pigment mixture. 